1. Field of the Invention
The present invention relates the digital fabrication of metallic articles, more specifically metallic articles manufactured using inkjet technology.
2. Description of the Related Art
Inkjet printing systems are being installed for different industrial applications because of their enhanced reliability and their flexibility in use, such as variable data printing making short production runs and personalized products possible at low cost.
Metallic articles or components are conventionally made using CNC machines. The initial startup cost is high due to the setup of CNC machines, but the cost per component is then usually reduced by volume production. Generally the cost also increases with the shape complexity. Sometimes, the shape complexity becomes too high to be economically viable or even too complex to be produced by these conventional tools.
3D inkjet printing is today offered as an industrial inkjet production tool. Most 3D inkjet printing systems deliver articles formed in an organic material and not in metal. There is one 3D inkjet printing system available, known as the Digital Metal™ technology from Höganäs (see: http://www.hoganas.com/en/business-areas/digital-metal/technology/), which delivers inkjet printed stainless steel components and possibly in the future also titanium, silver and copper components. The technology involves printing the stainless steel component layer by layer by jetting an ink on a metal powder, followed by sintering for strength and a surface quality improving treatment, such as peening, blasting or tumble finishing. The technology offers tolerances of 100 μm, with holes and wall thicknesses down to 200 μm. The layer by layer inkjet printing, as well as the energy-consuming sintering and the surface finishing decrease the productivity substantially. Furthermore, metallic articles having details below 100 μm and thickness of less than 200 μm cannot be produced by this technology.
Another method for manufacturing metallic articles is disclosed by US 2011020970 (SUN CHEMICAL), which discloses a process of etching or plating comprising the steps of: i) ink jet printing an alkali removable water insoluble hot melt ink jet ink onto a substrate to form a resist image; ii) etching or plating the substrate in an aqueous acid medium; and iv) removing the resist image with an aqueous alkali. A hot melt ink is solid at 25° C. This physical property has a large advantage in the achievable image quality on a cold metal surface as it solidifies rapidly after a jetted ink droplet lands on the metal surface. However, this physical property also has a detrimental effect on productivity. Etching speed is reduced as it has to be performed at lower temperatures, usually around room temperature to 35° C., where the ink does not melt or soften. For accelerating the removal of ink, organic solvents are often added to remove water insoluble hot melt ink jet inks from a metal surface.
Hence, there is still a need for improved digital fabrication methods of metallic articles allowing short production runs at high productivity and at low cost and this for a wide variety of metals and alloys.